As the high-profile trial of Jian Ghomeshi opened Monday, a woman who alleges she was sexually assaulted twice by the former CBC radio host testified that he twice pulled her hair and on one occasion punched her in the head multiple times after they started kissing at his home.

"He pulls my head down, and at the same time, he's punching me in the head, multiple times," the woman, whose identity is protected by a publication ban, said in Ontario Court in Toronto.

"I'm terrified. I don't know why he's doing this, I don't know if he's going to stop. Can I take this pain? And my ears are ringing, and I felt like I was going to faint. I'm going to end up passed out on his floor. And I start to cry."

The credibility of the woman's testimony was later challenged aggressively by Ghomeshi's lawyer, Marie Henein, who called into question her recollection of key events.

Ghomeshi, 48, who lives in Toronto, has pleaded not guilty in court to four counts of sexual assault and one count of overcoming resistance by choking, all related to assaults alleged to have taken place from 2002 to 2003. The trial is by judge only and is being heard by Judge William Horkins.

Wearing a charcoal suit, Ghomeshi sat silent in the courtroom, occasionally scribbling down notes during the trial.

The woman said the two had met at a Christmas party in 2002 and that they had been flirting with one another. She described Ghomeshi, the former host CBC Radio's Q, who at the time was hosting the CBC show Play, as "charming, fun, happy, charismatic."

She said he later invited her to a taping of his show, which she said she attended two days later. After the taping, she said they went to a nearby pub, then he drove her to her car at a nearby parking lot.

She said she felt safe with Ghomeshi, which was reinforced by the car he drove, a yellow Volkswagen Beetle, she told court.

"He's driving a car that reminds me of a 1960s Disney movie," she said. "So, I'm feeling very safe at the moment, when I'm with him."

Grabbed hair

When they got to the parking lot, they began kissing in his car, she said. Suddenly and unexpectedly she said Ghomeshi grabbed her hair "very hard."

She said that it was an instant switch and that Ghomeshi suddenly reverted "to the nice guy and I questioned whether he actually meant to hurt me."

"I was thinking, 'Perhaps he doesn't know his own strength. Or ... in the future, this is something we'll have to sort out."

'He went from being really nice, to this rage. Dark.'- Witness in Ghomeshi trial

The woman said she went to three tapings of Play. At the third taping, the witness said she brought a friend with her. The two women and Ghomeshi later went to a pub, but only the complainant and Ghomeshi went back to his place.

She said they were on his couch, kissing and then they stood up and continued kissing. She said that's when Ghomeshi went behind her, pulled her hair, pulled her to her knees, and then punched her in the right side of her head.

"He went from being really nice, to this rage. Dark."

She said she wasn't sure if he used a closed or open fist, but that it felt like a closed fist.

'Threw me out like trash'

"After I start crying, Jian says, 'You should go now' or 'You better go now, I'll call you a cab,'" the witness said."He didn't apologize, he didn't ask if I was OK. He threw me out like trash."

She said she waited inside his home for about 10 minutes for the cab, and then went to her friend's house.

Crown attorney Michael Callaghan asked the woman if there had been any prior discussion about Ghomeshi hitting her.

"Absolutely no discussion," she said.

Ghomeshi's trial will take place in this courtroom in front of a judge alone in the Ontario Court of Justice. (CBC)

Witness cross-examined

During cross-examination, Henein challenged key details of the woman's testimony.

The defence lawyer said that Ghomeshi did not have a Volkswagen Beetle at the time of their meeting but did have a GTI (Volkswagen Golf) and that Ghomeshi purchased the Beetle "months and months" after their meeting.

The witness said she had a recollection of a bright yellow car that looked like a Beetle.

Henein also questioned the witness about two interviews she gave to the CBC where she failed to mention that she and Ghomeshi had been kissing before he allegedly pulled her hair the first time in his car.

"That was a lie," Henein said.

"That was not a lie," the witness said, adding that she was nervous during the interviews, that getting into all the details was embarrassing and she wasn't sure of the memory of kissing at that time.

The witness first lodged a complaint with Toronto police on Nov. 1. The next day, she wrote an email to police saying that she believed she was wearing hair extensions. But she has since retracted that statement, saying that in fact she was not wearing hair extensions.

"I take it you agree that if you had worn extensions ... that it would be odd that your hair was pulled so hard and the extensions didn't end up in Mr. Ghomeshi's hand? Right?" Henein asked.

"I was not wearing extensions," the witness replied.

Henein also quizzed the witness on another email she had sent police, in which she said Ghomeshi had smashed her head against the window of the car. The witness agreed with Henein that that had not occurred but that her head had been leaning up against the window.

The witness said in that email to police she had been thinking out loud, trying to remember events and that she didn't choose her words carefully. She said she had told a friend that had she been closer to the window, her head would have smashed into the glass. But the information that was relayed to police was that Ghomeshi had smashed her head against the window.

"When I wrote that to [police], it was incorrect," she said.

​Earlier, Henein asked the witness if she had told her friend after her first meeting with Ghomeshi that she was "smitten" with him, impressed that he was famous, and taken aback by him.

'I really liked him,' witness testifies

Henein asked her if she had said she wanted to see him again, was very excited about seeing him again and that she couldn't stop talking about him.

"I will accept that I really liked him. I thought he was a really nice person, intelligent and charming and a gentleman. It was that one incident that I had that I was unsure if it was just him not knowing his own strength," she said, adding that she did want to see him again.

Ghomeshi faces a separate trial in June on another charge of sexual assault. He was originally charged with seven counts of sexual assault, but the Crown withdrew two of those charges in May, saying there was no reasonable prospect of conviction.

The charges in today's trial stem from complaints made by three women. The woman testifying today alleges Ghomeshi sexually assaulted her on two occasions. Two of the women's identities are protected under a publication ban, but one of the complainants, actress Lucy Decoutere, went to court to waive that right.​

Ghomeshi fired by CBC

The CBC fired Ghomeshi in October 2014 after executives saw what they described as graphic evidence — consisting of videos, photos and text messages — that he had physically injured a woman.

In a lengthy Facebook post following his dismissal, Ghomeshi admitted to engaging in rough sex with his partners, but said it was always consensual.

But media reports quickly followed in which several women alleged Ghomeshi physically and sexually attacked them without their consent.